The present invention relates to waste processing systems for handling hazardous or radioactive waste which must be totally enclosed and in which material is dumped and shredded before being conveyed for further treatment or incineration and, more particularly, to a door assembly for providing a sealed environment in an air lock of the waste processing system.
Environmental laws require that hazardous material, including radioactive material, either be incinerated, stabilized or processed under certain prescribed conditions, or collected, packaged and stored at special sites. In any case, it is desirable to reduce the particle size of the material as much as possible. In the case of material to be incinerated, small particle size insures more complete combustion and facilitates feeding into an incinerator. In the case of material to be packaged, reduction of particle size allows a greater amount of material to be shipped within a given container. In the case of materials to be stabilized, small particle size insures more complete stabilization. In the case of material to be processed in a slagging mode incinerator, small particle size insures more complete breakdown of materials.
Since the handling of such material may give rise to toxic or radioactive fumes, or create the hazard of an explosion, it is desirable to process such material in enclosed environments. For example, in Robertson U.S. Pat. No. 5,022,328, there is disclosed a system in which containerized waste is conveyed upwardly through an elevator, then horizontally to an air lock where the containerized waste is dumped through a drop chute into a shredder device which grinds the waste material and containers, then is injected by a feed screw into an incinerator. A disadvantage with this system is that the material is elevated and conveyed horizontally in a system which is not enclosed or protected from the environment. Further, the system disclosed in the Robertson patent is not capable of receiving and dumping hazardous or radioactive material from reusable containers. Accordingly, there is a need for a waste processing system in which material can be received at ground level or intermediate levels, then processed for storage, stabilization, incineration or additional processing in a totally enclosed environment at a different level. Further, such a system should be able to handle reusable containers.